Make invalid search input explicit in UI and API

apps/api/views.py

@@ -1,5 +1,7 @@
 from rest_framework import generics
+from rest_framework import status
 from rest_framework.pagination import PageNumberPagination
+from rest_framework.response import Response
 from rest_framework.throttling import AnonRateThrottle, UserRateThrottle
 
 from apps.competitions.models import Competition, Season
@@ -39,17 +41,35 @@ class PlayerSearchApiView(ReadOnlyBaseAPIView, generics.ListAPIView):
     serializer_class = PlayerListSerializer
     pagination_class = ApiPagination
 
+    def get_search_form(self):
+        if not hasattr(self, "_search_form"):
+            self._search_form = PlayerSearchForm(self.request.query_params)
+        return self._search_form
+
+    def _validation_error_response(self):
+        form = self.get_search_form()
+        return Response(
+            {
+                "detail": "Invalid search parameters.",
+                "errors": form.errors.get_json_data(escape_html=True),
+            },
+            status=status.HTTP_400_BAD_REQUEST,
+        )
+
+    def list(self, request, *args, **kwargs):
+        form = self.get_search_form()
+        if form.is_bound and not form.is_valid():
+            return self._validation_error_response()
+        return super().list(request, *args, **kwargs)
+
     def get_queryset(self):
-        form = PlayerSearchForm(self.request.query_params or None)
+        form = self.get_search_form()
         queryset = base_player_queryset()
-        if form.is_valid():
-            queryset = filter_players(queryset, form.cleaned_data)
-            sort_key = form.cleaned_data.get("sort", "name_asc")
-            if sort_key in METRIC_SORT_KEYS:
-                queryset = annotate_player_metrics(queryset, form.cleaned_data)
-            queryset = apply_sorting(queryset, sort_key)
-        else:
-            queryset = queryset.order_by("full_name", "id")
+        queryset = filter_players(queryset, form.cleaned_data)
+        sort_key = form.cleaned_data.get("sort", "name_asc")
+        if sort_key in METRIC_SORT_KEYS:
+            queryset = annotate_player_metrics(queryset, form.cleaned_data)
+        queryset = apply_sorting(queryset, sort_key)
         return queryset